VIETNAM?S COASTAL MANAGEMENT: GOVERNANCE, EFFECTIVENESS AND SUSTAINABILITY

Ph.DDOCTOR OF PHILOSOPH

Identification of nutrient composition of some isolated microalgae from mangroves of Xuan Thuy national park

Microalgae species, such as Amphiprora alata, Chaetoceros muelleri, Nannochloropsis oculata, Navicula tuscula and Chlorella vulgaris from mangrove area of Xuan Thuy National Park are usually used as food sources for fishes, shrimps and bivalves and very environment friendly. The samples of these microalgae were enriched, isolated and purified in F/2 medium with salinity of 20%. The purifed colonies were cultured in media with different salinity in 14 days to find out the most optimal medium for the best growth as well as the stage yielding maximum living mass. These microalgae were then cultured in their optimal media at salinity of 25% until they reached their maximum living mass stage. They were cultivated and analyzed of their fatty acid, protein carbonhydrate components and percentages. The research has identified 24 fatty acids in 5 phytoplankton species. Unsaturated fatty acids components of Chaetoceros muelleri, Nannochloropsis oculata are the highest (76,35% and 71,17%), and fatty acid components of are medium Chlorella vulgaris and Amphiprora alata (59,24% and 52,21%), meanwhile, Navicula tuscula has 29.56% of unsaturated fatty acids.  Amphiprora alata and Chlorella vulgaris have protein content of 8.1g per 100g dry weight and 4.44g per 100g dry weight accordingly. Carbohydrate content of Nannochloropsis oculata and Navicula tuscula are 11.8g per 100g dry weight and 5.47g per 100g dry weight, respectively.

Synthesis of antiulcer drug esomeprazole.

Esomeprazole (Nexium®), the (S)-isomer of Omeprazole, is the first proton-pump inhibitor developed as a single isomer for the treatment of acid-related diseases. It is used for the treatment of peptic ulcers, gastroesophagal reflux disease, and erosive esophagitis. Herein, we report our synthetic study of esomeprazole sodium salt from the starting    2-mercapto-5-methoxybenzimidazole and 2-(chloromethyl)-4-methoxy-3,5-dimethylpyridine hydrochloride reagents. The Esomeprazole sodium salt was obtained from enantioselectivesulfoxidation reaction in moderate yield with high enantioselectivity

NONLINEAR CHARACTERISTICS OF SQUARE SOLID-CORE PHOTONIC CRYSTAL FIBERS WITH VARIOUS LATTICE PARAMETERS IN THE CLADDING

Nonlinear characteristics of fused silica, solid-core photonic crystal fibers (PCFs) with a square array of air holes are studied numerically. We present a novel design that emphasizes the difference in air hole diameters in the photonic cladding. These PCFs have the advantages of flat dispersion, high nonlinearity, and low attenuation. Based on simulation results, three optimal structures, denoted #F1, #F2, and #F3, having anomalous and all-normal dispersions in the near-infrared range are selected to investigate characteristic properties at the pump wavelength. Such PCFs open up many possibilities for nonlinear optical applications, especially supercontinuum generation

INFLUENCE OF STRUCTURAL PARAMETERS ON OPTICAL CHARACTERISTICS OF PHOTONIC CRYSTAL FIBERS WITH CIRCULAR LATTICE

We demonstrate in this study that near-zero, ultra-flattened chromatic dispersion can be achieved over a wide range of wavelengths in photonic crystal fibers (PCFs) by means of slight variations in the geometrical parameters of the cladding. To do that, a new solid-core circular PCF design with various air hole diameters and lattice constants is presented, and the design features are numerically analyzed in detail. After 40 simulations, we determined three structures that possess optimal dispersion with the following lattice constants (Ʌ) and filling factors for the first ring (d1/Ʌ): Ʌ = 0.8 µm, d1/Ʌ = 0.45 for #F1, Ʌ = 0.9 µm, d1/Ʌ = 0.45 for #F2, and Ʌ = 1.0 µm, d1/Ʌ = 0.45 for #F3. High nonlinearity and low attenuation are outstanding features of our model. With these advantages, the proposed fibers are targeted for smooth flat broadband supercontinuum generation for near-infrared applications

Eupolauridine alkaloids of Polyalthia nemoralis

Two eupolauridine alkaloids, eupolauridine (1) and 8-methoxyeupolauridine (2), together with a phenanthrene compound, 2,7-dihydroxy-3,6-dimethoxyphenanthrene (3), were isolated from the ethyl acetate extract of Polyalthia nemoralis barks. Their structures were elucidated on the basis of spectroscopic analysis and comparison with related known compounds. These compounds were evaluated the cytotoxicity on seven human cancer cell lines including KB, MCF7, LU-1, HepG2, LNCap, SW626 and SW480